Lecture 7: Desert ecosystems and caryophylalles Flashcards
What clade contains many families that produce betalain pigments in place of anthyocyanin?
Caryophyllid clade
What are some common traits in the Caryophyllales clade?
- Unique and different seed anatomy
- Production of betalain pigments in place of anthyocyanin
- Often adapted to extreme habitats that may be dry, salty, high sulfur, high/low phosphorous soils
- Wood production not common and has different anatomy than in other taxa
What order is the Caryophyllaceae family in?
Caryophyllales
Where is the habitat of the Caryophyllales family?
Common in temperate regions
What are the leaf/stem characteristics of the Caryophyllaceae family?
- herbaceous
- opposite leaves
- swollen nodes
What are some flower characteristics of the Caryophyllaceae family?
- flowers arranged in cymes
- flowers perfect, radial, 4-5 sepals, 4-5 petals, which may be fused at the base or not
- notched/split or clawed petals
- 10 stamens
- 2-5 carpels; it is not possible to see how many carpels in the ovary due to free-central placentation–but can count the stigma/styles
- superior ovary
What type of fruit in the Caryophyllaceae family?
Capsules
What is unique about the perianth in the Caryphyllaceae family?
5-merous flowers with petals often bifid (split), sometimes appearing almost like 10 petals
fused sepals
What clade is the Amaranthaceae in?
Caryophyllales
What two genera are in the Amaranthaceae family?
Amaranthus and Chenopodium
–> two important weeds
What is the habitat of Amaranthaceae family?
Important in desert ecosystems since they are many salt tolerant species (weeds, ornamental plants, and vegetables)
What are some examples of vegetables in the Amaranthaceae family?
Beets, spinach, quinoa, other grains, etc.
What are some characteristics of Amaranthus genus?
- herbaceous
- annual plants
- often spiny inflorescences of small flowers
- simple leaves
- alternative leaves
- spiny bracts
What are some characteristics of Chenopodium genus?
- herbaceous plants or shrubs
- alternate simple leaves
- plants often salt-tolerant (halophytic)
- often stems, leaves, and sepals have a gritty texture (mealy surface)
- no spines next to flowers
Where is the Cactaceae family endemic to?
the Americas
What are some leaf/stem characteristics of the Cactaceae family?
- Xeromorphic plants with succulent, photosynthetic stems that have stomata and usually no bark
- Lateral branches modified into areoles with non-expanding stems and leaves changed to spines
What are some flower characteristics of the Cactaceae family?
- Flowers solitary
- Radial or bilateral symmetry
- Flowers perfect
- Inferior ovary, often with tubular epigynous hypanthium
- Many petals
- Many stamens
- Often several carpels
What type of fruit in the Cactaceae family?
Berry (technically a berry surrounded by a fleshy hypanthium)
What are aeroles?
Each areole represents a reduced lateral branch in which the leaves have been modified into spines
Flowers and new stems also may grow from them
What order is the Polygonaceae (buckwheat) family a part of?
Caryophyllales
What type of placentation in the Polygonaceae family?
Basal placentation –> does not have the unique embryological characters of other Caryophyllids
What are some stem/leaf characteristics of the Polygonaceae (buckwheat) family?
- Herbs or shrubs with alternate leaves
- Sheathing stipules called ochrea
What are some flower characteristics of Polygonaceae?
- Flowers relatively small
- Perfect or unisexual
- Ovary superior with 2-3 fused carpels with 1 seed
- Flowers with either 3 inner and 3 outer tepals (of similar texture but different size) or 5-6 tepals in a single whorl
- Stamens 2-9, often 6-8
What type of fruit in the Polygonaceae family?
Achene with three sides
What is an ochrea?
A sheathing stipule
What are some characteristics of Fallopia japonica?
- Perennial, herbaceous plant
- Invasive especially along banks of waterways
- Not very shade tolerant
- Very good at establishing itself on coarse soil
Which order is the Droseraceae family a part of?
Caryophyllales
What are some characteristics of Droseraceae?
Carnivorous plants not traditionally associated with Caryophyllids, but they form a claude with them in phylogenetic trees based on both nuclear and chloroplast DNA sequences
Unique habitats with challenging nutrient acquisition common in order
Often found in fens and bogs
Flower not important in identification
What are some characteristics of Drosera genus?
- Small plants with basal rosette of leaves
- Leaves with glandular hairs to capture insects (insectivorous)
- Perfect flowers
What are some characteristics of deserts?
Low levels of precipitation; most less than 10 inches a year
Potential evapotranspiration exceeds precipitation
Can occur at different average annual temperatures and precipitation levels
- some areas lose water more than others, number of hours of sunlight, etc. impact this
In North American desert regions, there are several mountain ranges/isolated mountains
- these provide large gradients in temperature and precipitation/moisture availability
Water deficit –>
Where is precipitation low globally?
At equator high sun intensity causes evaporation and a moist warm air mass to rise
As it rises, this air mass moves away from the equator, cools and releases moisture (in wet tropics region)
Cool, dry air falls at 30 degreed N or S latitude, causing bands of deserts at these regions
What are challenging environmental conditions found in deserts?
Large fluctuations in day/night temperatures because few clouds to capture reflected infrared radiation, so no sun, no heat
Exposed soils (because of incomplete cover of vegetation) lead to high rates of weathering and erosion (since more sun exposure, more temperature fluctuations, exposure to wind) and very low OM content
Some deserts have salt concentrated at the surface because of evaporation from the soil bringing salts to the surface and not enough heavy rains to leach the salts out of the soil
What are some plant interactions/adaptations in deserts?
Mutualistic/facilitation types of exchange are important/more frequent than in more productive environments for plant growth
Competition for resources still occurs, but the harsh growing conditions mean that being close to a neighbour might be more of an aid than a hinderance
Main positive exchanges: protection from herbivores, microhabitat of shade, wind blocking, and hydraulic lift from deeper rooted neighbours
What are characteristics that make different regions have somewhat distinctive deserts?
Topography, continental location, geologic history, etc.
What are four bigger named regions of deserts?
Great Basin
Mojave
Sonoran
Chihuahuan
What is an important factor that influences species distribution at a local scale?
Topography
What are some characteristics of the Great Basin desert (#5)?
Northern
Shrubby woody plants dominate
Less diverse than other desert regions
Western side of NA
What type of vegetation at in basins at mid-elevations vs. lower elevations?
Mid-elevation: dominated by woodlands
Lower elevations: sparse grasslands to desert shrub
What is a species that is dominant in the Great Basin shrublands?
Sagebrush –> deep roots bring water to the surface
What are characteristics of Playa (closed lake basins?
During the last glaciation, these basins were flooded, but as the climate dried, the lowest part of the basin became dry, salty deposit where few plants can grow
What are some characteristics of the Sonoran Desert (#10)?
High diversity
Habitats vary greatly with topography
Indicator species: Cactaceae
Spring habitats harbor remnants of the flora that prospered when the region was wetter during and after the last glaciation
Rivers and streams are also present
What type of vegetation found in Sonoran desert?
Lower lands: Fabaceae trees common
Mesquite
Cactaceae
Asteraceae
Papaveraceae
Salicaceae
etc.
What are some characteristics of the Mojave desert (#9)?
A transitional desert at fairly high elevations, parts with a good water supply, but also Death Valley
Joshua tree is the indicator species for this desert
Yucca (Asparagaceae family)
What are some charactersitics of the Chihuahuan desert (#12)?
High-elevation warm desert in Texas, New Mexico and Mexico
Limestone and calcareous soils common
Rich diversity of Cactaceae and Asparagaceae: Agovoideae subfamily
Indicator species: Agave lechuguilla
